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West Nile virus has evolved in concert with its expansion across North America, but little is known about the evolutionary dynamics of the virus on local scales. We analysed viral nucleotide sequences from mosquitoes collected in 2005, 2006, and 2007 from a known transmission ‘hot spot’ in suburban Chicago, USA. Within this approximately 11 × 14 km area, the viral envelope gene has increased approximately 0.1% yr−1 in nucleotide-level genetic diversity. In each year, viral diversity was higher in ‘residential’ sites characterized by dense housing than in more open ‘urban green space’ sites such as cemeteries and parks. Phylodynamic analyses showed an increase in incidence around 2005, consistent with a higher-than-average peak in mosquito and human infection rates that year. Analyses of times to most recent common ancestor suggest that WNV in 2005 and 2006 may have arisen predominantly from viruses present during 2004 and 2005, respectively, but that WNV in 2007 had an older common ancestor, perhaps indicating a predominantly mixed or exogenous origin. These results show that the population of WNV in suburban Chicago is an admixture of viruses that are both locally derived and introduced from elsewhere, containing evolutionary information aggregated across a breadth of spatial and temporal scales.  相似文献   

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The migratory history of Sakhalin taimen, Hucho perryi, was examined in terms of strontium (Sr) and calcium (Ca) uptake in the otolith by using wavelength dispersive X-ray spectrometry on an electron microprobe. Otolioth Sr:Ca ratios of freshwater-reared samples remained consistently at low levels throughout the otolith. The Sr:Ca ratios of samples from Lake Aynskoye of Sakhalin Island showed a low value from the core up to a point of 700–2140µm. Thereafter, the ratios increased sharply and remained at higher levels up to the outermost regions. The difference in Sr:Ca ratio might be the result of the presence of individuals that underwent seawater and freshwater life history phases, probably reflecting the ambient salinity or the seawater–freshwater gradient in Sr concentration. Otolith Sr:Ca ratio analysis revealed downstream migration history in H. perryi.  相似文献   

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[BPy]H2PO4 was easily prepared and used as an efficient and recyclable catalyst for the one-pot synthesis of 2,4,5-trisubstituted imidazoles under solvent-free conditions in good to excellent yields. Solvent-free conditions, simple experimental and workup procedures, and the use of a nontoxic, recyclable catalyst of an environmentally benign nature are remarkable features of the procedure.  相似文献   

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Workplace training offers a distinctly explicit and uniquely articulate site for the ethnography of the capital–labor relation as an ideological phenomenon, where the everyday work of hegemony is shown to be deeply grounded in the everyday hegemony of work. In this ethnographic account of a factory classroom devoted to introducing production workers to the precepts of Total Quality Management and training them in Statistical Process Control, the neoliberal reform of the labor process—which sought to accomplish a class decomposition of the company’s workforce in favor of an individualizing regime of workers’ personal responsibility and accountability for various quality control operations—repeatedly provoked the company’s Latino workers into angry and vociferous expressions of antagonism to management. Indeed, insofar as the management’s efforts to reform labor by decomposing the workforce as a class formation merely intensified the prevailing preconditions of their racial formation, they thereby only exacerbated anew the Latino workers’ antagonism as workers to the terms of their subordination. Thus, the generic (ostensibly race-neutral) reform of the labor process initiated under the aegis of “Total Quality Management” implicated the presumed management of “quality” in a concomitant reconfiguration of what was, effectively, a contemporary regime of racial management.  相似文献   

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